Superchargers have become pervasive in automobiles, boats, aircraft, and commercial stationary engines as the need to maximize power output has increased due to the use of smaller engines. Centrifugal superchargers employ a high-speed impeller to develop their boost pressure. Although such high-speed machinery places extreme demands on the associated drive machinery, e.g., bearings, seals, shafts, housing components, and the like, centrifugal compressors benefit from very high thermodynamic efficiencies, resulting in optimum engine outputs.
Most centrifugal superchargers employ some sort of speed increasing mechanism to provide the rotation speed for the centrifugal compressor portion of the device to work. This mechanism, which is usually comprised of two parallel shafts with either a belt or gear system connecting them, requires matching cylindrical bores for the shafts and bearings. In the current art, a minimum of two bearing bores and two locating pin bores are machined in each part that comprise the supercharger case and cover, and the two are assembled like two halves of a clam shell, e.g. the separating plane of the individual case components is orthogonal to both shafts. This process requires eight (8) precision boring operations. A significant problem exists in manufacturing the very precise bores of the case components. For example, the accuracy needed to obtain the desired relationship between the two shafts requires true position and parallelism tolerances of 0.0005 inches. These extremely tight tolerances challenge the capabilities of even the newest and best state-of-the-art computer-controlled machining centers. Manufacturing these assemblies requires expensive and time-consuming set-up, machining, measuring and matching procedures. Even with very careful manufacturing procedures, a significant component rejection rate exists, due to parts that do not meet the strict tolerance requirements.
In view of the above, there exists a need for an efficient supercharger that is easy to manufacture and service.